In industrial usage of machine vision for inspection of parts, monitoring processes and the like, elaborate and expensive vision systems are often employed to acquire and store images of a scene in digital form and analyze the images to extract certain information such as the dimensions of objects, the position or orientation of objects or the presence of visible defects on an object. Usually such systems are required to perform repetitive operations on massive amounts of data and yield results in a very short time. A number of expensive general purpose machine vision systems are commercially available to meet these needs but are often economically unfeasible for applications requiring only a few of their capabilities.
It sometimes happens that a machine vision system can be demonstrated successfully in an ideal setting yet fails to perform consistently in a day-to-day factory operation. Often the lighting varies too much for the system to cope with or dirt build-up affects camera performance. Often, these conditions can be dealt with by the system but may require system redesign or reprogramming, and the extra operations may make the machine too slow to be acceptable. In some cases the system lacks the capabilities for overcoming the problems.
To overcome these problems, an interface unit or preprocessor has been developed to improve the quality of the video signal from the camera before it enters the vision processor. In particular, it uses single structured functions to manipulate stored digital video information and is set up to execute constantly repeatable set functions. The video enhancer has been made to be inexpensive and versatile. To achieve the flexibility necessary to suit varied applications and to deal with sundry problems, it is designed to be easily programmable and very easy for operators to use. It has been found, however, that due to its programmability, it sometimes can carry out the entire vision process and in those cases it can be used as a cost effective replacement for a general purpose vision machine that is several times more expensive.